Objectives Although dementia typically occurs in older people, it can also emerge in people aged younger than 65 years in the form of young‐onset dementia, the most common type of which is Alzheimer's disease (AD). However, few studies have examined the needs of persons with young‐onset AD (YO‐AD) and their families, and cross‐cultural research on the topic is even scarcer. In response, we investigated the situations, experiences and needs for assistance of carers of persons with YO‐AD in Brazil and Norway. Methods As part of our qualitative study, we formed a convenience sample of Brazilian (n = 9; 7 women) and Norwegian carers (n = 11; 6 women) in 2014 and 2015, respectively, and analysed data in light of a modified version of grounded theory. Results Carers' narratives from both countries revealed five common themes in terms of how YO‐AD affected carers' psychological and emotional well‐being, physical well‐being, professional and financial well‐being, social lives and need for support services. Conclusions The infrequent differences between carers of persons with YO‐AD in Brazil and Norway indicate that carers' problems are highly similar regardless of cultural differences and public services provided. Copyright © 2017 John Wiley & Sons, Ltd.